Conventionally, there is known a centrifugal compressor in which guide blades (vanes) that are arranged between an impeller and a scroll and are provided in a diffuser flow path, the vanes decreasing and pressurizing a fluid having a speed increased by the impeller.
For example, Patent Document 1 describes an invention that controls the positions of vanes in accordance with the flow rate of air in a diffuser flow path (airflow rate). For example, the vanes protrude into the diffuser flow path for low airflow rates, and do not protrude into the diffuser flow path for high airflow rates.